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The anode oxygen evolution reaction (OER) in electrochemical water splitting hinders the cathode hydrogen evolution reaction (HER) due to its larger thermodynamic barrier and slow kinetic process, while the anode hydrazine oxidation reaction (HzOR) provides an alternative way to solve this problem. Meanwhile, metal-based electrocatalysts frequently appear in cathodic reactions due to their excellent electrical conductivity and catalytic performance. However, the susceptibility to oxidation of metals limits their application in anodic reactions. Herein, we successfully introduced cobalt (Co) metal as a host material to synthesize the MoO2/Co heterojunction for the electrocatalytic reaction, which can achieve a current density of 10 mA cm−2 at −48 mV for the HER and −73 mV for the HzOR. Moreover, the two-electrode overall hydrazine splitting (OHzS) electrolyzer requires an extremely small cell voltage of 35 mV for 10 mA cm−2. DFT calculations demonstrate that MoO2 and Co can simultaneously optimize the free energy of hydrogen adsorption (ΔGH*) and the stepwise dehydrogenation process of N2H4 benefiting from the constructed heterojunction. This research designs an innovative method of developing metal-incorporated materials for the study of enhanced bifunctional electrocatalysts and improves an energy-efficient H2 generating technology. [ABSTRACT FROM AUTHOR]

Lead halide perovskite has triggered a lot of research due to its superior optical properties. However, halide perovskite materials have poor environmental stabilities and are easily affected by external factors such as water and heat, resulting in structural decomposition and performance failure. Contrary to this commonplace concept, it is found that CsPbBr3 (CPB) can convert to CsPb2Br5 (CP2B5) partially when meeting a small amount of water, and the CsPbBr3@CsPb2Br5 (CPB@CP2B5) composite is synthesized by an in situ method accordingly. The CPB@CP2B5 composite shows an enhanced catalytic performance compared with pure CPB, as well as a dramatically synergistic effect of photo and thermal for catalytic CO2 hydrogenation. The CO production rate of CPB@CP2B5 is determined as 69 μmol g−1 h−1 under light irradiation at 200 °C, which is 156.8 and 43.4 times higher than that under pure photo (0.44 μmol g−1 h −1) and pure thermal (1.59 μmol g−1 h −1) condition, respectively. Meanwhile, the CPB@CP2B5 sample is also stable, which shows no significant decline in the catalytic activity during 8 cycles of repeated experiments. The probable mechanism is explored by utilizing a series of in situ characterizations. [ABSTRACT FROM AUTHOR]

The energy-upconversion of lanthanide-doped nanoparticles with a core–shell structure can be utilized to enhance and tune optical properties and can generate multifunctionality in a single system. Herein, the core–shell nanoparticles NaYF4:Yb,Ho,Tm@NaGdF4 were prepared by thermally decomposing lanthanide acetylacetonate precursors. Through modifying the molar ratio of the core and shell, nanodumbbell-shaped particles with different sizes and morphologies were precisely synthesized. The formation mechanism and the heterogeneous epitaxial growth process of the nanodumbbell-shaped particles were studied. After coating the shell layer, upconversion luminescence intensities, spectral purity and fluorescence lifetimes were improved. Furthermore, the magnetic performance of the core–shell nanoparticles was characterized. The optical–magnetic bifunctional upconversion core–shell particles with programmable shape and multiple properties provide an ideal platform for the preparation of nanodumbbell-shaped particles and the promotion of upconversion materials for biomedical research. [ABSTRACT FROM AUTHOR]

Severe poisonousness and prolonged instability existing in organic-inorganic lead-based perovskite are two matters seriously hindering its potential future application in photocatalysis. Therefore, it is particularly important to explore ecology-friendly, air-stable and highly active metal-halide perovskites. Herein, a new and stable lead-free perovskite Cs 2 SnBr 6 decorated with reduced graphene oxide (rGO), is synthesized and employed in the photocatalytic organic conversion. The as-prepared Cs 2 SnBr 6 is ultrastable, exhibiting no clear changes after being placed in the air for six months. The Cs 2 SnBr 6 /rGO composite shows excellent photocatalytic activity in photo-driven-oxidation of 5-hydroxymethylfurfural (HMF) to high value enclosed 2,5-diformylfuran (DFF), achieving>99.5 % conversion of HMF and 88 % DFF selectivity in the presence of green oxidant O 2 . Comprehensive characterizations disclose a multistep reaction mechanism, demonstrating that the molecular oxygen, photogenerated carriers, ⋅O 2 - and 1 O 2 altogether synergistically participate in the effective photo-driven conversion of HMF to DFF. This work expands the material gallery towards selective organic conversion and environmentally friendly perovskite options for photocatalytic application., (© 2023 Wiley-VCH GmbH.)

Lead halide perovskite has triggered a lot of research due to its superior optical properties. However, halide perovskite materials have poor environmental stabilities and are easily affected by external factors such as water and heat, resulting in structural decomposition and performance failure. Contrary to this commonplace concept, it is found that CsPbBr 3 (CPB) can convert to CsPb 2 Br 5 (CP2B5) partially when meeting a small amount of water, and the CsPbBr 3 @CsPb 2 Br 5 (CPB@CP2B5) composite is synthesized by an in situ method accordingly. The CPB@CP2B5 composite shows an enhanced catalytic performance compared with pure CPB, as well as a dramatically synergistic effect of photo and thermal for catalytic CO 2 hydrogenation. The CO production rate of CPB@CP2B5 is determined as 69 μmol g -1  h -1 under light irradiation at 200 °C, which is 156.8 and 43.4 times higher than that under pure photo (0.44 μmol g -1  h -1 ) and pure thermal (1.59 μmol g -1  h -1 ) condition, respectively. Meanwhile, the CPB@CP2B5 sample is also stable, which shows no significant decline in the catalytic activity during 8 cycles of repeated experiments. The probable mechanism is explored by utilizing a series of in situ characterizations., (© 2022 Wiley-VCH GmbH.)

Lead-free perovskites Cs 3 Bi 2 x Sb 2-2 x I 9 (x = 0.1, 0.3, 0.5, 0.7, 0.9) are prepared by a co-precipitation method and their photocatalytic performance for hydrogen production is studied in aqueous HI solution. Compared with the lead-based perovskite (CH 3 NH 3 )PbI 3 , Cs 3 Bi 2 x Sb 2-2 x I 9 has a better catalytic performance under air mass 1.5 G (AM 1.5 G) simulated sunlight (100 mW cm -2 ), powders of Cs 3 Bi 0.6 Sb 1.4 I 9 (100 mg) loaded with Pt nanoparticles show < H 2 evolution rate of 92.6 µmol h -1 , which greatly exceeds that of (CH 3 NH 3 )PbI 3 powders loaded with Pt nanoparticles (100 mg catalyst, 4 µmol h -1 ). The Cs 3 Bi 2 x Sb 2-2 x I 9 has a high stability, with no apparent decrease in catalytic activity after five consecutive H 2 evolution experiments. The doping of Sb in Cs 3 Bi 2 x Sb 2-2 x I 9 effectively reduces the contribution of Bi 3+ on the conduction band, attenuating the effect of Bi vacancy on band structure. Compared with pure Cs 3 Bi 2 I 9 and Cs 3 Sb 2 I 9 , Cs 3 Bi 2 x Sb 2-2 x I 9 has fewer midgap states and better optical absorption, which greatly enhances its performance for the hydrogen evolution reaction., (© 2020 Wiley-VCH GmbH.)

A facile and efficient photoreduction method is employed to synthesize the composite of methylammonium lead iodide perovskite (MAPbI 3 ) with reduced graphene oxide (rGO). This MAPbI 3 /rGO composite is shown to be an outstanding visible-light photocatalyst for H 2 evolution in aqueous HI solution saturated with MAPbI 3 . Powder samples of MAPbI 3 /rGO (100 mg) show a H 2 evolution rate of 93.9 µmol h -1 , which is 67 times faster than that of pristine MAPbI 3 , under 120 mW cm -2 visible-light (λ ≥ 420 nm) illumination, and the composite is highly stable showing no significant decrease in the catalytic activity after 200 h (i.e., 20 cycles) of repeated H 2 evolution experiments. The electrochemiluminescence performance of MAPbI 3 is investigated to explore the charge transfer process, to find that the photogenerated electrons in MAPbI 3 are transferred to the rGO sites, where protons are reduced to H 2 ., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The energy-upconversion of lanthanide-doped nanoparticles with a core-shell structure can be utilized to enhance and tune optical properties and can generate multifunctionality in a single system. Herein, the core-shell nanoparticles NaYF 4 :Yb,Ho,Tm@NaGdF 4 were prepared by thermally decomposing lanthanide acetylacetonate precursors. Through modifying the molar ratio of the core and shell, nanodumbbell-shaped particles with different sizes and morphologies were precisely synthesized. The formation mechanism and the heterogeneous epitaxial growth process of the nanodumbbell-shaped particles were studied. After coating the shell layer, upconversion luminescence intensities, spectral purity and fluorescence lifetimes were improved. Furthermore, the magnetic performance of the core-shell nanoparticles was characterized. The optical-magnetic bifunctional upconversion core-shell particles with programmable shape and multiple properties provide an ideal platform for the preparation of nanodumbbell-shaped particles and the promotion of upconversion materials for biomedical research.